Changes that are important to me may mean nothing to you. An example would be embedded album art being enabled. To some it was the greatest thing ever, and to others it was an absolute meh development.

The one question I see about as much as any other is "What happened to "X" theme?" If it's been a while since you've updated there may have been theme syntax changes that cause older themes to break. What's on the theme site now should work with the release and current builds.